Evaluation of the Properties of Geopolymer Concrete With the Addition of Bamboo Leaf Ash as a Natural Pozzolanic Material

Abstract

As a result of growing environmental concerns in the cement industry and rising costs of building materials, there has been an increased interest in alternative cement technologies. New binders are now necessary for better environmental and durability performance. For this study, geopolymer concrete containing industrial products (fly ash Class F) and agricultural wastes (calcined bamboo leaf ash) was chosen as a cement substitute in the making of concrete. This research was an experimental study evaluating the impact of bamboo leaf ash on geopolymer concrete by addition as a partial substitute of fly ash. The test samples were 100x100x100 mm cubes and 300x150mm cylinders at the environmental curing temperature. The target mix proportion of class 25 was used for this study. This research aimed to explore the suitability of the use of calcined bamboo leaf ash (BLA) as a mixing material in geopolymer concrete in more environmentally friendly industries. The properties that were investigated in this study are the basic aggregate tests, XRF analyses of BLA and fly ash class F; and workability tests by evaluating slump and compaction factor tests. Compressive strength and splitting tensile strength were also tested after curing at ambient temperature for 28, 56 and 90 days. Moreover, water absorption, sulphate resistance, acid resistance, and chloride attack were evaluated as part of the durability parameters. Therefore, in this study, various levels of bamboo leaf ash were utilized, including 0% (100% fly ash class F), 5%, 10%, 15%, and 20% BLA. The ratio of alkaline liquid to the binder for all mixes was fixed at 0.6, whereas the Na2SiO3 to NaOH proportion was 2.5 with a molarity (M) of 16. The findings of the workability test indicate that adding more bamboo leaf ash gradually decreases the liquid and leads the concrete to harden when compared to control samples without bamboo ash. Mechanical properties, such as compressive and splitting tensile strengths, indicated that the fly ash replacements containing 5% and 10% of the bamboo leaf had greater strengths than the other mixtures, measuring around 38.7 MPa, 40.8 MPa, 4 MPa, and 4.22 MPa, respectively. Results for the durability performance indicate that the water absorption of geopolymer concrete values increases with the increasing percentage of bamboo leaf ash by 2.46% up to 5.06%. While all samples exposed to 5% of MgSO4, H2SO4, and NaCl as an exposure solution indicate excellent resistance in terms of change in mass, variation of compressive strength, and change in appearance. Therefore, bamboo leaf ash (BLA) can be one of the constituent materials in geopolymer concrete when the concern is the aggressive environmental conditions and mechanical properties.